test(store): add header de/serialization fuzzing (#3514)

store/file/header_test.go

@@ -0,0 +1,53 @@
+package file
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+// Due to bug on macOS we need to specify additional linker flags:
+// 	go test -v -run=^$ -fuzz=Fuzz_writeReadheader -ldflags=-extldflags=-Wl,-ld_classic .
+
+func Fuzz_writeReadheader(f *testing.F) {
+	f.Add(uint8(0), uint8(0), uint16(0), uint16(0), []byte{31: 0})
+	f.Add(uint8(1), uint8(1), uint16(1), uint16(1), []byte{31: 0})
+	f.Add(uint8(1), uint8(1), uint16(1), uint16(1), []byte{100: 1})
+
+	f.Fuzz(func(t *testing.T, ver, typ uint8, shs, sqs uint16, b []byte) {
+		// we expect hash to be 32 bytes, crop or extend to 32 bytes.
+		diff := len(b) - 32
+		if diff > 0 {
+			b = b[:32]
+		} else {
+			pad := bytes.Repeat([]byte{0}, -diff)
+			b = append(b, pad...)
+		}
+
+		testHdr := headerV0{
+			fileVersion: fileVersion(ver),
+			fileType:    fileType(typ),
+			shareSize:   shs,
+			squareSize:  sqs,
+			datahash:    b,
+		}
+
+		w := bytes.NewBuffer(nil)
+		err := writeHeader(w, &testHdr)
+		if err != nil {
+			return
+		}
+
+		hdr, err := readHeader(w)
+		if err != nil {
+			return
+		}
+
+		require.Equal(t, hdr.fileType, testHdr.fileType)
+		require.Equal(t, hdr.fileType, testHdr.fileType)
+		require.Equal(t, hdr.shareSize, testHdr.shareSize)
+		require.Equal(t, hdr.squareSize, testHdr.squareSize)
+		require.Equal(t, hdr.datahash, testHdr.datahash)
+	})
+}